ArneA

Hello!

I recently purchased a non running 1981 SA rx7.

Transmission:

The car first shifted with some difficulty but after playing with it a little it shifts from 1 2 3 4 5 quite smoothly. When I try to get it into reverse it just feels like there is no reverse? I tried from 5th to reverse and from neutral to reverse and nothing seems to work.

Engine: (12A)

I removed the sparkplugs and sprayed some fogging oil into the engine while manually cranking it with a wrench trough the alternator pulley, the engine turns easily and smoothly, I get 3 even pulses from one side, but the other side gives me 1 solid pulse, a quiet one and then nothing. I could take the engine out with no issues with a crane, rebuild it properly using a video. The thing I'm scared of is the timing of the engine, I have no idea how it works and I don't want to mess things up. I have looked around a bit trying to find info about the timing of the engine but can't find something very clear. Is it hard to put the engine back in?

Thanks in advance!

7aull

iTrader: (2)

Hallo Arne-
Removing/installing the engine. When I did this, I removed most ALL the engine accessories first, so that the engine itself, which is then quite small, and much lighter to move, was removed by itself OFF the transmission. That is, I removed the engine and left the transmission in the car. You can remove the 2 as one unit, but it requires 2 people and obviously, being so big, it must be removed with care.

The engine is designed to come out by itself. You will see TWO hooks mounted to the top of the motor, one at the front, one at the back. These are for lifting it. Once the engine-to-transmission connecting bolts have been removed, it is helpful to put a lift-jack under the front of the transmission and lift it by tilting the front of the transmission upward. The idea is to first attach the lift to the engine and (after removing the engine mounting bolts at the front of the motor so that it is free) as it hangs off its mounts, lift up the transmission so it tilts up. The lifting chains of the motor should be set so that the FRONT of the motor is tilting up at an angle as you lift and remove it. You are trying to get enough of an angle to make it easier to slide the engine rear off the transmission's drive shaft that is inserted into the back of the motor.

To install you keep the transmission at this same 'Lifted" angle with the jack to make it easier to slip the engine back on to the shaft.

Timing the engine. I can't offer a lot of information here, but others can. But a couple of points:
-the MAIN pulley has the timing marks on it. I believe on the 1981+ FB RX7s (as we call them over here, not SA), you can ONLY mount the pulley to the motor ONE way so you will have the timing marks of the pulley on the correct position on the main shaft.
-before you remove the DISTRIBUTOR, make a mark to show its current position as it sits in the engine. The idea is you want to later RE-insert the Distributor in this correct position! There is a particular way the Distributor will sit into the bottom of the engine hole that it will "click" into place. This is described in the repair manuals. It is critical the Distributor is correctly inserted to do this!

NONE of this sets the Timing for you, but it DOES have everything in the correct place so you CAN then adjust the Timing. It is very likely that the timing in the engine is already pretty close to correct. At least enough so that when you try to start your rebuilt engine, it will run well enough to then adjust the timing.

Best of luck. If you have good Build videos (I did) then the rebuild process is (or seems) pretty simple and logical.

Stu Aull
80GS
Arizona, USA

t_g_farrell

iTrader: (1)

Relax and just realize you can have the timing completely off by 90 or 180 degrees and it won't break or ruin any parts of the engine unlike on a typical interference piston engine. Theres no valves!

If the timing is off it may still run, just poorly. Easy to fix once the engine is back in place.

ArneA

Thank you so much for the help, it was kind of a depressing moment, I get 25 PSI of compression everywhere, not higher than that, the transmission gets into reverse now, it was just me not knowing it needs an extra push to the right to get it in there,And thanks once again for the tips, I will certainly keep them in mind!

KYPREO

The apex seals on 1 rotor might be stuck. This can happen with excessive carbon buildup and sitting for a long time.

Have you tried cranking with the starter motor? are you using a rotary compression tester? You won't get proper compression reading without a rotary compression tester at sufficiently high rpm. Manually cranking it will not do, especially if the seals are stuck.

Before pulling the engine, you can try to use auto trans fluid to loosen the carbon and unstick the seals. Read up here:

Tricks to Loosen Stuck Apex Seals - AusRotary

ATF Trick - AusRotary

EDIT: I think it's also worth taking off the exhaust and visually inspecting the seals through the exhaust ports to see if they are broken or just stuck.

ArneA

I now tested it with the starter, I get 25 PSI max on both sides, not sure what this means, I only know that this is very low
The top spark plugs are entirely black and covered in carbon, the bottom ones aren't
Was done with a normal tester, I might fill it with ATF but will remove the exhaust first, just wondering what stuck apex seals look like? Or is the engine entirely screwed?

7aull

iTrader: (2)

A stuck seal means it is compressed and locked into the groove at the apex of a rotor tip. So air/fuel just blow past on the compression cycle. It is spring-loaded (ie there is a spring under it to keep it 'popped' out of the top edge of the groove). If it is stuck and the spring compressed, usually from sitting and carbon baked on it to hold it there, you need to dissolve the carbon. People are recommending ATF to do this, as it presumably (I have not used it) dissolves the carbon, releases the spring and the apex seal pops up to the correct position.

This is a quick and easy start to solving your problem re: lack of compression. If the apex seals are worn to low, or the spring under one has failed, then a rebuild is the next step.

No advantage to removing the exhaust first. Keep the engine sealed up to let the ATF do its magic!

Stu Aull
80GS
AZ

Jeff20B

iTrader: (13)

Try regular engine oil instead of ATF. The engine was designed to have a little bit of oil in it, but ATF is nasty when it burns.

GSLSEforme

^^^^ +1